Disclaimer

  • References: Nigeria Centre for Disease control (NCDC), see here:

Nigeria Center for Disease Control and Prevention

Nigeria Center for Disease Control and Prevention
  • More information: for a dynamic report of the 🇳🇬 Lassa fever situation in Nigeria , go to 🔗

Lassa fever in Nigeria - data from 2020 to 2024

The overall burden of Lassa fever in Nigeria

  • Nigeria has the highest burden of Lassa fever cases in West Africa.
  • Strengthening of capacity for lab diagnostics and case management in previous years resulted in greater case detection.
  • Major LF outbreaks reported in since 2018, with 5344 confirmed cases since 2020.

The effect of seasonality on the Lassa fever incidence

  • Lassa fever cases in Nigeria by week show a seasonal effect: the number of cases peaks during the dry season period (from epi week 47 - week 12).
  • The seasonal increase of cases during the dry period may be attributed to an increase of the infected rodent population and/or a seasonal behavioural change in the human population resulting in a higher risk of exposure to infected animals and/or to food/household items contaminated with rodent excreta.

  • Lassa fever cases in Nigeria by week show a seasonal effect: the number of cases peaks during the dry season period (from epi week 47 - week 12).
  • The seasonal increase of cases during the dry period may be attributed to an increase of the infected rodent population and/or a seasonal behavioural change in the human population resulting in a higher risk of exposure to infected animals and/or to food/household items contaminated with rodent excreta.

Lassa fever in Nigeria: where do efforts need to focus?

From January 2018 to December 2024, 75% of Lassa fever confirmed cases were from Ondo (33%), Edo (31%) and Bauchi (11%).

  • Total suspected cases: 41,270
  • Total confirmed cases: 6,083
  • Deaths from Confirmed Cases: 1,117
  • Case Fatality Ratio: 21%
  • Number of Health Care Workers: 234

Lassa fever suspected cases, confirmed cases and CFR by State, Nigeria 2020-2024

Lassa fever by State, Nigeria 2020-2024: Interactive maps

Suspected cases of Lassa fever

  • From 2017-2024, a total of 36,022 suspected cases were reported from 26 in Zamfara to 13,950 in Edo.

Case fatality rate (CFR) among confirmed Lassa fever cases

  • From 2017-2024, CFR among all lab confirmed cases in Nigeria was between 16-27% and decreased over time.
  • In 2024, overall CFR for Nigeria was 16% and differed greatly by individual State.
  • The variation in CFR is likely due to late patient presentation and differences in case management, highlighting the need for improvement.

Lassa fever infections among healthcare workers

  • From 2020-2024, a total of 212 healthcare workers (HCW) were reported among confirmed cases, that is 4% of Lassa fever cases.
  • From 2020-2024, 60% of all HCW infections were from Ondo (26%), Bauchi (20%), Edo (15%) States where 75% of all Lassa fever patients were being cared for. 12% of HCW infections are reported from Ebonyi where 6% of Lassa fever patients were being cared for.
  • Higher proportion of HCW in States with low incidence (10-30%).

Lassa fever in 2025 - Data from epi-week 1 to epi-week 21

Suspected cases of Lassa fever in 2025

  • In 2025, a total of 5,248 suspected cases were reported from 1 in Jigawa, Osun to 1,692 in Ondo.

Cumulative number of confirmed Lassa fever cases in 2025

  • Nigeria has the highest burden of Lassa fever cases in West Africa.
  • Strengthening of capacity for lab diagnostics and case management in previous years resulted in greater case detection.
  • Major LF outbreaks reported in since 2018, with 5344 confirmed cases since 2020.

Seasonality of Lassa fever

  • In 2025, similar trend as per previous years confirming a seasonal effect on Lassa fever incidence.
  • Compared to 2024, 19% decrease in the cumulative number of suspected cases reported.

  • In 2025, similar trend as per previous years confirming a seasonal effect on Lassa fever incidence.
  • Compared to 2024, 18% decrease in the cumulative number of confirmed cases reported.

States reporting Lassa fever confirmed cases in 2025

  • In 2025, as of epi week 21, 87% of LF cases are from Ondo (30%), Bauchi (25%), Edo (16%), and Taraba (16%) States.

  • Total confirmed cases: 739

  • Deaths from Confirmed Cases: 141

  • Case Fatality Ratio: 19%

  • Number of Health Care Workers: 22

Lassa fever suspected cases, confirmed cases and CFR by State in 2025

Lassa fever by State, Nigeria 2025: Interactive maps

Case fatality ratio among confirmed Lassa fever cases by State in 2025

  • As of epi week 21 2025, cumulatively 739 cases and 141 deaths (CFR=19%) across 18 States have been reported.
  • At same period 2024, a total of 28 States reported at least one confirmed cases.
  • There is a 19% decrease in the number of suspected cases reported in 2025 compared to 2024.
  • There is a 18% decrease in the number of confirmed cases reported in 2025 compared to 2024.
  • In 2024,
    • 37 States had reported at least one suspected case versus 34 States in 2025 to date.
    • 28 States had reported at least one confirmed case versus 18 States in 2025 to date.

Health care worker infections 2020-2025 epiweek 21


  • Top 5 states:
    • 8 HCW infections in Ondo
    • 4 HCW infections in Bauchi
    • 3 HCW infections in Taraba
    • 2 HCW infections in Edo
    • 2 HCW infections in Gombe.

  • As of epi week 21 of 2025, there has been 22 healthcare workers infected, that is 3% of confirmed cases.

Lassa fever in most affected States - Data from 2020 to 2025 (as of epi-week 21)

Lassa fever in Ondo State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Ondo as of week 21:
Years Suspected cases Confirmed cases Deaths CFR
2025 1692 224 28 12%
2024 1410 226 16 7%
2023 1578 308 33 11%
2022 813 219 40 18%
2021 375 84 24 29%
2020 645 332 52 16%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Ondo State reported 224 confirmed cases including 28 deaths (CFR 12%).
  • Compared to same period 2024, this represents:
    • 20% increase in the number of suspected cases.
    • 1% decrease in the number of confirmed cases.
    • 77% increase in CFR.




  • In 2024 as of week 21:
    • 1410 in the number of suspected cases.
    • 226 in the number of confirmed cases.
    • 16 in the number of deaths.
    • 7% average CFR.




  • In 2023 as of week 21:
    • 1578 in the number of suspected cases.
    • 308 in the number of confirmed cases.
    • 33 in the number of deaths.
    • 11% average CFR.




  • In 2022 as of week 21:
    • 813 in the number of suspected cases.
    • 219 in the number of confirmed cases.
    • 40 in the number of deaths.
    • 18% average CFR.




  • In 2021 as of week 21:
    • 375 in the number of suspected cases.
    • 84 in the number of confirmed cases.
    • 24 in the number of deaths.
    • 29% average CFR.




  • In 2020 as of week 21:
    • 645 in the number of suspected cases.
    • 332 in the number of confirmed cases.
    • 52 in the number of deaths.
    • 16% average CFR.

Lassa fever in Bauchi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Bauchi as of week 21:
Years Suspected cases Confirmed cases Deaths CFR
2025 835 185 16 9%
2024 781 157 29 18%
2023 697 106 20 19%
2022 677 115 12 10%
2021 61 10 2 20%
2020 282 44 20 45%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Bauchi State reported 185 confirmed cases including 16 deaths (CFR 9%).
  • Compared to same period 2024, this represents:
    • 7% increase in the number of suspected cases.
    • 18% increase in the number of confirmed cases.
    • 53% decrease in CFR.




  • In 2024 as of week 21:
    • 781 in the number of suspected cases.
    • 157 in the number of confirmed cases.
    • 29 in the number of deaths.
    • 18% average CFR.




  • In 2023 as of week 21:
    • 697 in the number of suspected cases.
    • 106 in the number of confirmed cases.
    • 20 in the number of deaths.
    • 19% average CFR.




  • In 2022 as of week 21:
    • 677 in the number of suspected cases.
    • 115 in the number of confirmed cases.
    • 12 in the number of deaths.
    • 10% average CFR.




  • In 2021 as of week 21:
    • 61 in the number of suspected cases.
    • 10 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 20% average CFR.




  • In 2020 as of week 21:
    • 282 in the number of suspected cases.
    • 44 in the number of confirmed cases.
    • 20 in the number of deaths.
    • 45% average CFR.

Lassa fever in Edo State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Edo as of week 21:
Years Suspected cases Confirmed cases Deaths CFR
2025 1556 121 20 17%
2024 1669 196 26 13%
2023 2106 274 35 13%
2022 1558 193 27 14%
2021 1137 125 14 11%
2020 1305 328 39 12%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Edo State reported 121 confirmed cases including 20 deaths (CFR 17%).
  • Compared to same period 2024, this represents:
    • 7% decrease in the number of suspected cases.
    • 38% decrease in the number of confirmed cases.
    • 25% increase in CFR.




  • In 2024 as of week 21:
    • 1669 in the number of suspected cases.
    • 196 in the number of confirmed cases.
    • 26 in the number of deaths.
    • 13% average CFR.




  • In 2023 as of week 21:
    • 2106 in the number of suspected cases.
    • 274 in the number of confirmed cases.
    • 35 in the number of deaths.
    • 13% average CFR.




  • In 2022 as of week 21:
    • 1558 in the number of suspected cases.
    • 193 in the number of confirmed cases.
    • 27 in the number of deaths.
    • 14% average CFR.




  • In 2021 as of week 21:
    • 1137 in the number of suspected cases.
    • 125 in the number of confirmed cases.
    • 14 in the number of deaths.
    • 11% average CFR.




  • In 2020 as of week 21:
    • 1305 in the number of suspected cases.
    • 328 in the number of confirmed cases.
    • 39 in the number of deaths.
    • 12% average CFR.

Lassa fever in Taraba State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Taraba as of week 21:
Years Suspected cases Confirmed cases Deaths CFR
2025 313 116 34 29%
2024 227 99 21 21%
2023 272 93 29 31%
2022 84 32 15 47%
2021 55 18 11 61%
2020 111 56 21 38%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Taraba State reported 116 confirmed cases including 34 deaths (CFR 29%).
  • Compared to same period 2024, this represents:
    • 38% increase in the number of suspected cases.
    • 17% increase in the number of confirmed cases.
    • 38% increase in CFR.




  • In 2024 as of week 21:
    • 227 in the number of suspected cases.
    • 99 in the number of confirmed cases.
    • 21 in the number of deaths.
    • 21% average CFR.




  • In 2023 as of week 21:
    • 272 in the number of suspected cases.
    • 93 in the number of confirmed cases.
    • 29 in the number of deaths.
    • 31% average CFR.




  • In 2022 as of week 21:
    • 84 in the number of suspected cases.
    • 32 in the number of confirmed cases.
    • 15 in the number of deaths.
    • 47% average CFR.




  • In 2021 as of week 21:
    • 55 in the number of suspected cases.
    • 18 in the number of confirmed cases.
    • 11 in the number of deaths.
    • 61% average CFR.




  • In 2020 as of week 21:
    • 111 in the number of suspected cases.
    • 56 in the number of confirmed cases.
    • 21 in the number of deaths.
    • 38% average CFR.

Lassa fever in Ebonyi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Ebonyi as of week 21:
Years Suspected cases Confirmed cases Deaths CFR
2025 237 21 11 52%
2024 268 43 24 56%
2023 208 50 28 56%
2022 217 39 18 46%
2021 88 17 8 47%
2020 223 75 21 28%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Ebonyi State reported 21 confirmed cases including 11 deaths (CFR 52%).
  • Compared to same period 2024, this represents:
    • 12% decrease in the number of suspected cases.
    • 51% decrease in the number of confirmed cases.
    • 6% decrease in CFR.




  • In 2024 as of week 21:
    • 268 in the number of suspected cases.
    • 43 in the number of confirmed cases.
    • 24 in the number of deaths.
    • 56% average CFR.




  • In 2023 as of week 21:
    • 208 in the number of suspected cases.
    • 50 in the number of confirmed cases.
    • 28 in the number of deaths.
    • 56% average CFR.




  • In 2022 as of week 21:
    • 217 in the number of suspected cases.
    • 39 in the number of confirmed cases.
    • 18 in the number of deaths.
    • 46% average CFR.




  • In 2021 as of week 21:
    • 88 in the number of suspected cases.
    • 17 in the number of confirmed cases.
    • 8 in the number of deaths.
    • 47% average CFR.




  • In 2020 as of week 21:
    • 223 in the number of suspected cases.
    • 75 in the number of confirmed cases.
    • 21 in the number of deaths.
    • 28% average CFR.

Lassa fever in Kogi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Kogi as of week 21:
Years Suspected cases Confirmed cases Deaths CFR
2025 69 15 4 27%
2024 119 29 3 10%
2023 39 11 1 9%
2022 116 44 7 16%
2021 7 2 0 0%
2020 91 38 8 21%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Kogi State reported 15 confirmed cases including 4 deaths (CFR 27%).
  • Compared to same period 2024, this represents:
    • 42% decrease in the number of suspected cases.
    • 48% decrease in the number of confirmed cases.
    • 158% increase in CFR.




  • In 2024 as of week 21:
    • 119 in the number of suspected cases.
    • 29 in the number of confirmed cases.
    • 3 in the number of deaths.
    • 10% average CFR.




  • In 2023 as of week 21:
    • 39 in the number of suspected cases.
    • 11 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 9% average CFR.




  • In 2022 as of week 21:
    • 116 in the number of suspected cases.
    • 44 in the number of confirmed cases.
    • 7 in the number of deaths.
    • 16% average CFR.




  • In 2021 as of week 21:
    • 7 in the number of suspected cases.
    • 2 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2020 as of week 21:
    • 91 in the number of suspected cases.
    • 38 in the number of confirmed cases.
    • 8 in the number of deaths.
    • 21% average CFR.

Lassa fever in Gombe State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Gombe as of week 21:
Years Suspected cases Confirmed cases Deaths CFR
2025 69 14 7 50%
2024 29 4 2 50%
2023 38 8 2 25%
2022 189 20 8 40%
2021 6 0 0 –
2020 34 9 2 22%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Gombe State reported 14 confirmed cases including 7 deaths (CFR 50%).
  • Compared to same period 2024, this represents:
    • 138% increase in the number of suspected cases.
    • 250% increase in the number of confirmed cases.
    • 0% decrease in CFR.




  • In 2024 as of week 21:
    • 29 in the number of suspected cases.
    • 4 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 50% average CFR.




  • In 2023 as of week 21:
    • 38 in the number of suspected cases.
    • 8 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 25% average CFR.




  • In 2022 as of week 21:
    • 189 in the number of suspected cases.
    • 20 in the number of confirmed cases.
    • 8 in the number of deaths.
    • 40% average CFR.




  • In 2021 as of week 21:
    • 6 in the number of suspected cases.
    • 0 in the number of confirmed cases.
    • 0 in the number of deaths.
    • NA average CFR.




  • In 2020 as of week 21:
    • 34 in the number of suspected cases.
    • 9 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 22% average CFR.

Lassa fever in Benue State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Benue as of week 21:
Years Suspected cases Confirmed cases Deaths CFR
2025 74 11 5 45%
2024 1046 62 11 18%
2023 149 36 3 8%
2022 195 32 8 25%
2021 21 6 0 0%
2020 34 9 4 44%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Benue State reported 11 confirmed cases including 5 deaths (CFR 45%).
  • Compared to same period 2024, this represents:
    • 93% decrease in the number of suspected cases.
    • 82% decrease in the number of confirmed cases.
    • 156% increase in CFR.




  • In 2024 as of week 21:
    • 1046 in the number of suspected cases.
    • 62 in the number of confirmed cases.
    • 11 in the number of deaths.
    • 18% average CFR.




  • In 2023 as of week 21:
    • 149 in the number of suspected cases.
    • 36 in the number of confirmed cases.
    • 3 in the number of deaths.
    • 8% average CFR.




  • In 2022 as of week 21:
    • 195 in the number of suspected cases.
    • 32 in the number of confirmed cases.
    • 8 in the number of deaths.
    • 25% average CFR.




  • In 2021 as of week 21:
    • 21 in the number of suspected cases.
    • 6 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2020 as of week 21:
    • 34 in the number of suspected cases.
    • 9 in the number of confirmed cases.
    • 4 in the number of deaths.
    • 44% average CFR.

Thank you

Any questions or suggestions? Contact us: Anaïs Legand and Antoine Chaillon